Activated charcoal has long been used as a filter aid with both liquids and gases for the purpose of clarifying liquids and deodorizing liquids and gases.
In recent times it has been proposed as for example in British Specification No. 1,270,809 to incorporate activated charcoal into a fibre web or mat, the web or mat being supported by a backing material such as cloth obtained from natural sources as cotton, or formed of a synthetic such as nylon, and shaped so that the resulting web fits into and covers the inner sole of a shoe. It has also been proposed to attach a layer or coating of a foam material such as polyurethane foam to such a web for the purpose of providing increased strength and springiness.